Catheters having inflatable balloons mounted on their distal ends are a commonly used apparatus for entering blood vessels to expand and open strictures at remote sites in a non-invasive manner.
In conventional balloon catheters, vessel expansion is achieved by inflating the balloon on the catheter tip at the site of the obstruction. The balloon expands radially outward, thereby expanding the place in the blood vessel where it is located.
One disadvantage of the conventional balloon catheter is that blood flow through the lumen of the vessel in which the balloon is to be inflated, which is already severely reduced because of the stricture, is momentarily completely cut-off when the balloon is inflated and exerting pressure against the stricture-causing mass and/or wall of the vessel. If such a condition is maintained for an extended period of time it is possible that damage to or necrosis of the tissue material of the vessel wall may occur.
Accurate control of the extent of inflation of the balloon may also be difficult to achieve in some circumstances with conventional balloon catheters. If inflation is not carefully monitored and controlled, it is possible to overinflate the balloon which in turn may cause a stretching and weakening of the vessel wall.
In the particular application of balloon catheters to angioplasty, moreover, there is a possibility, which occurs at a frequency on the order of about 5% of the cases, of the abrupt reclosure of an expanded artery after balloon angioplasty. This is generally due to a dissection of the arterial wall obstructing the lumen, to elastic recoil of the arterial wall, or to spontaneous spasm of the arterial wall.